Body fluids include all types of liquid phase substances contained in a body of an animal or a human. Although body fluids in general refer to whole blood, lymph, urine, saliva, sweat and the like, the present invention is particularly related to blood and urine of a human body (a patient for example).
Measurement of urine volume of a patient is an important factor for the evaluation of circulating blood volume.
A human body goes into a circulatory collapse state due to the direct reduction of circulatory blood volume such as blood loss, burns and so on caused by all kinds of accidents or surgeries, and due to the indirect reduction of circulatory blood volume such as sepsis (blood infection) and heart failure (myocardial infarction, arrhythmia, etc.). When such occurs, small arteries contracts regardless of whether the autonomic (sympathetic and parasympathetic) nervous system is under conscious control, and this affects blood volume to be supplied to every organ in the body.
Among the organs, a kidney suffers the most serious arterial contraction. This is because it is the kidney that filters blood flowing therein to thereby form urine, thereby contributing to the reduction of a circulating blood volume.
Under the neural regulation of the autonomic nervous system, contraction of kidney arteries plays a role in blocking the volume of blood flow into the kidney in the early stage of hematozemia and a role in suppressing urine production, so that the circulating blood volume can be preserved. However, if this state is continued over the span of hours (6 hours or longer), renal cells get severely damaged and acute tubular necrosis (ATN), a kidney disorder associated with the development of acute renal failure, may occur or permanent kidney failure may be resulted in, depending on the conditions of a patient.
In field or clinical experiences, if a patient loses much blood because of internal diseases or during accidents/surgeries, he is provided with fluid (Ringer's solution: physiological saline) to prevent the above-described side effects and further to normalize the circulating blood volume. This consequently induces the relaxation in the small arteries supplied to the kidney, and prevents necrosis in renal tubule cells.
One of the most crucial criteria that shows whether a proper circulating blood volume is restored after the physiological saline was replenished, and whether an adequate volume of blood flow is provided into the kidney, is measuring the urine volume. In effect, urine volume is the very first thing medical staffs check in a patient after loss of the circulating blood volume was replenished through the fluid (Ringer's solution).
Monitoring an intake with an output of the body, one can evaluate whether or not the kidney is properly functioning and whether a proper volume of the blood is being circulated.
Some of specific constituents contained in blood and urine are used as very important criteria for the evaluation of renal function.
Information in Table 1 below is used in a real clinical experience to check a patient's condition.
TABLE 1GFR (glomerular filtration ratio): Criteria: Creatinine clearance (Ccr)(Normal range of GFR: 150 L/day or 100 mL/min)Ccr (ml/min) = (Urine Cr × Volume/Plasma Cr)Urine Cr: mg/dl, Volume: mL/min, Plasma Cr: mg/dL
As can be seen in Table 1, urine volume, and creatine (Cr) in urine or in blood shows a value of Cr clearance, and its value reflects GFT (glomerular filtration ratio), namely, the clearing capability or filtering ability of the kidney, useful for the renal function test.
TABLE 2Pre-renal ARFIntrinsic renal ARFFormula(n value)(n value)Cr ratio = Urine>40>20Cr/Plasma CrPlasma BUN/Cr ratio>20Nitrogen ratio = Urine>8BUN/Plasma BUNUrine Osmolarity>500Specific gravity>1,018Concentration of Na+ in>20Urine★ FE Na+ = Urine (Na+/<1>1Cr)/Plasma (Na+/Cr)★ Renal Failure Index =<1>1U (Na+)/GFR = UrineNa+/(urine Cr/Plasma Cr)
As can be seen in Table 2, when constituents of blood and urine, i.e., Cr, BUN, and Na+, Osmolarity, specific gravity and so on are known, one can estimate a cause of ARF. ‘Pre-renal ARF’ in Table 2 indicates that the cause already existed, meaning that the deficiency of blood volume itself results from diseases. ‘Intrinsic renal ARF’ indicates that the kidney itself has a problem, meaning that damages are brought on renal cells by various causes.
Among the criteria, FE Na+ value and Renal Failure Index value marked with ★ are the most accurate, and therefore used as the most valuable criteria in field.
For instance, if the result of FE Na+ obtained by substituting Na+ and Cr concentrations in the equation is greater than 1, it indicates renal failure due to damaged renal cells of a patient. On the other hand, if the result is less than 1, it means that the patient's kidney functions normally but the circulating blood volume is deficient. In like manner, results of the Renal Failure Index can be utilized.
As such, measurement of urine volume and specific constituents in blood and in urine signifies much about patients suffering from direct, acute blood loss because of accidents, surgeries, burns and so on, or patients with internal diseases.
Besides the evaluation of acute renal diseases, the measurement can enable early diagnosis and prognosis of a chronic renal disease, that is, an accurate monitoring of the progress of a disease. Typical examples of such are heart failures like diabetic chronic renal disease.
On the other hand, most critically ill patients and ABR (absolute bed rest) patients are hospitalized due to various internal diseases. For medical management of such a patient group, a Foley catheter is currently used.
The Foley catheter passes through a urethra into a patient's bladder and is held therein through blooning. The urine stored in the bladder through the Foley catheter is collected in a urine bag by internal pressure, and the accumulated urine volume is measured through the scaled marked on the bag.
Basically, operating procedure requires the insertion of the Foley catheter from the entrance of the urethra down to the bladder, so a patient feels a lot of pain during the procedure. In addition, it may cause a secondary infection such as urinary system infection and contributes to the mass production of antibiotic resistant strains in a hospital. If the urinary system infection through the Foley catheter results in hematogenous infection, it may prove fatal. It has been reported that if the urinary system infection progresses to the hematogenous infection, the mortality rate reaches approximately 30% (refer to Internal Medicine Cecil).
In a hospital, if symptoms of infection, e.g., chill, fever etc., are actually observed after the Foley catheter insertion operation required for measurement of urine volume in a real time mode, the first step is to remove the Foley catheter, administer a suitable antibiotic, and carry out postprocessing depending on the course. Unfortunately if the patient has an underlying disease, he might permanently lose renal function.
The conventional technique for measurement of urine volume by reading scales marked on the urine bag connected to the Foley catheter has three major problems as follows:
First of all, it is not reliably accurate. The urine bag has different shapes depending on how it is fixed to the bedside and what state it is in, and those different shapes give different scales on an actual height of the urine volume accumulated in the bag. This type of scale reading has a great margin of observational error.
Secondly, it is neither convenient nor efficient. Although it may be different depending on the condition of a patient, if a doctor gives an order to measure the urine volume, a nurse or the patient's patron or caregiver should personally check urine in the urine bag every hour. If an emergency patient comes to the ward, all staff in the hospital pay attention to that patient, so other patients except for the emergency patient naturally lose interest of doctors.
Thirdly, it causes a secondary infection through the Foley catheter. This is actually the most serious problem, with about 30% of patients who have the Foley catheter operation reported to suffer from the urine system infection 1 week after the operation (refer to General Surgery Sabiston). This urinary system infection increases 3 to 5% every day. If it is neglected more than 2 weeks, almost every patient will suffer from the urinary system infection (refer to Internal Medicine Cecil).
As an attempt to solve the above-described problems, the inventors have suggested diverse urine collecting instruments for more conveniently collecting urine from patients with and without urination troubles like dysuria.
Korean Patent Application Nos. 2000-47602, 2000-58206, 2001-86938, and 2002-44362 filed by the same inventors disclosed a urine collecting apparatus that automatically senses urine, sucks and cleanses the urine with a bidet, even for use with an unconscious patent.
Even though these inventions improved the reading accuracy of the existing urine bag in that they measure the urine volume through the scales marked on a urine container, they still require an individual to personally read the scales for measurement. After all, the inventions show no improvement in the inconvenient conventional method, and do not consider constituents of the urine, either.
In addition, in case of the previously disclosed inventions, the urine collecting apparatus has the structure shown in FIG. 9, where a urine container 26 for keeping a urine case is installed on the rear end portion of the apparatus and a urine passage 27 is extended in a longitudinal direction and at the same time, the crooked passage is directed against gravity as shown in the drawing. Therefore, if the apparatus is used for an extended period of time, urinary calculus is easily formed in the passage, easily producing odor if the apparatus is not maintained in hygienic conditions.
Moreover, because the urine container and a scrubbing water container are installed in the same space, it is highly likely that the scrubbing water container becomes contaminated rather easily, in spite of strong demand for hygiene standards therefor.
Meanwhile, the existing analysis of constituents in a body fluid is generally made with help of an instrument in a clinical laboratory. For the analysis, a specific chemical is first added to the body fluid and a spectrum is used to analyze constituents therein. Normally, it takes more than 24 hours from the analysis to informing the analysis results to the medical staff concerned. The reason for delay is because technicians in the laboratory do not always handle one single urine sample of a particular individual but they test urines of all patients hospitalized in a hospital, label their body fluid samples, analyze batches of the samples, and match the analysis results with names of the respective patients.